1. Field of the Disclosure
The following is directed to solid oxide fuel cells (SOFCs) and methods of forming SOFCs, and particularly directed to a single, sintering process of forming a SOFC unit cell.
2. Description of the Related Art
A fuel cell is a device that generates electricity by a chemical reaction. Among various fuel cells, solid oxide fuel cells (SOFCs) use a hard, ceramic compound metal (e.g., calcium or zirconium) oxide as an electrolyte. Typically, in solid oxide fuel cells, an oxygen gas, such as O2, is reduced to oxygen ions (O2−) at the cathode, and a fuel gas, such as H2 gas, is oxidized with the oxygen ions to form water at the anode.
In some instances, fuel cells assemblies have been designed as stacks, which include a cathode, anode, and solid electrolyte between the cathode and the anode. Each stack can be considered a subassembly, which can be combined with other stacks to form a full SOFC article. In assembling the SOFC article, electrical interconnects can be disposed between the cathode of one stack and the anode of another stack.
However, stacks of individual fuel cells can be susceptible to damage caused by fluctuation in temperature during their formation or use. Specifically, materials employed to form the various components, including ceramics of differing compositions, exhibit distinct material, chemical, and electrical properties that can result in breakdown and failure of the SOFC article. In particular, fuel cells have a limited tolerance for changes in temperature. Problems associated with mechanical stress caused by changes in temperature are exacerbated when individual fuel cells are stacked. Limited thermal shock resistance of fuel cells, particularly of fuel cells assembled in stacks, limits the yield of production and poses a heightened risk of failure during operation.
Moreover, the fabrication of SOFC articles has its own set of concerns. Concerns associated with layering and sintering of the compositionally different layers is one of the most formidable challenges in SOFC manufacturing. Current approaches focus on multi-step firing processes and the use of metallic interconnect materials. The industry continues to demand improved SOFC articles and methods of forming.